xal.extension.solver.algorithm

Class RandomShrinkSearch

java.lang.Object

xal.extension.solver.algorithm.SearchAlgorithm

xal.extension.solver.algorithm.RandomShrinkSearch

All Implemented Interfaces:

AlgorithmScheduleListener, SolutionJudgeListener

public class RandomShrinkSearch
extends SearchAlgorithm

RandomSearchAlgorithm looks for points bounded by the specified variable limits. Every iteration a subset of variables are randomly chosen to be changed. The value chosen for each variable is randomly selected from a uniform distribution within a window for that variable. The window begins as the full limit range allowed by the variable. Whenever a better solution is found, the window changes so that it is three times wider than the distance between the last best point and the new best point. The window gets centered around the new best points. Then the window gets clipped as necessary to satisfy the variable limits. Note that the window may grow or shrink depending on the distance between successive top points. As the optimal solution is approached, the window should tend to shrink around the optimal point. Note that each variable has its own window and the window automatically adjusts to the variable according to the progress.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	RandomShrinkSearch.ComboSearcher Use a combination of search engines to search for the best solution.
protected class	RandomShrinkSearch.RandomSearcher A searcher that performs a simple random search in the entire search space.
protected static interface	RandomShrinkSearch.Searcher Interface for classes that search for solutions.
protected class	RandomShrinkSearch.ShrinkSearcher ShrinkSearcher searches for the next trial point by adjusting the search domain per variable depending on how much a variable has changed between the best solutions found so far.

Field Summary

Fields

Modifier and Type	Field and Description
protected TrialPoint	_bestPoint The current best point.
protected RandomShrinkSearch.Searcher	_searcher The active search technique (random or shrink).

Fields inherited from class xal.extension.solver.algorithm.SearchAlgorithm

_eventProxy, _messageCenter, _problem

Constructor Summary

Constructors

Constructor and Description
RandomShrinkSearch() Empty constructor.

Method Summary

Modifier and Type	Method and Description
void	algorithmAvailable(SearchAlgorithm source) Handle a message that an algorithm is available.
void	algorithmUnavailable(SearchAlgorithm source) Handle a message that an algorithm is not available.
void	foundNewOptimalSolution(SolutionJudge source, java.util.List<Trial> solutions, Trial solution) Handle a message that a new optimal solution has been found.
java.lang.String	getLabel() Get the label for this search algorithm.
int	globalRating() Get the rating for this algorithm which in an integer between 0 and 10 and indicates how well this algorithm performs on global searches.
int	localRating() Get the rating for this algorithm which in an integer between 0 and 10 and indicates how well this algorithm performs on local searches.
TrialPoint	nextTrialPoint() Calculate and get the next trial point to evaluate.
void	performRun(AlgorithmRun algorithmRun) Calculate the next few trial points.
void	reset() reset for searching from scratch; forget history
protected void	resetBestPoint() Reset the trial point's variables to their starting values.
void	setProblem(Problem problem) Set the specified problem to solve.

Methods inherited from class xal.extension.solver.algorithm.SearchAlgorithm

addSearchAlgorithmListener, getMaxEvaluationsPerRun, getMinEvaluationsPerRun, removeSearchAlgorithmListener, strategyExecuted, strategyWillExecute, trialScored, trialVetoed

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_bestPoint

protected TrialPoint _bestPoint

The current best point.

_searcher

protected RandomShrinkSearch.Searcher _searcher

The active search technique (random or shrink).

Constructor Detail

RandomShrinkSearch

public RandomShrinkSearch()

Empty constructor.

Method Detail

setProblem

public void setProblem(Problem problem)

Set the specified problem to solve. Override the inherited method to look for hints.

Overrides:

setProblem in class SearchAlgorithm

Parameters:

problem - the problem to solve

getLabel

public java.lang.String getLabel()

Get the label for this search algorithm.

Specified by:

getLabel in class SearchAlgorithm

Returns:

The label for this algorithm

reset

public void reset()

reset for searching from scratch; forget history

Overrides:

reset in class SearchAlgorithm

resetBestPoint

protected void resetBestPoint()

Reset the trial point's variables to their starting values.

performRun

public void performRun(AlgorithmRun algorithmRun)

Calculate the next few trial points.

Specified by:

performRun in class SearchAlgorithm

Parameters:

algorithmRun - the algorithm run to perform the evaluation

nextTrialPoint

public TrialPoint nextTrialPoint()

Calculate and get the next trial point to evaluate.

Returns:

The next trial point to evaluate.

globalRating

public int globalRating()

Get the rating for this algorithm which in an integer between 0 and 10 and indicates how well this algorithm performs on global searches.

Returns:

The global search rating for this algorithm.

localRating

public int localRating()

Get the rating for this algorithm which in an integer between 0 and 10 and indicates how well this algorithm performs on local searches.

Returns:

The local search rating for this algorithm.

algorithmAvailable

public void algorithmAvailable(SearchAlgorithm source)

Handle a message that an algorithm is available.

Parameters:

source - The source of the available algorithm.

algorithmUnavailable

public void algorithmUnavailable(SearchAlgorithm source)

Handle a message that an algorithm is not available.

Parameters:

source - The source of the available algorithm.

foundNewOptimalSolution

public void foundNewOptimalSolution(SolutionJudge source,
                                    java.util.List<Trial> solutions,
                                    Trial solution)

Handle a message that a new optimal solution has been found.

Specified by:

foundNewOptimalSolution in interface SolutionJudgeListener

Overrides:

foundNewOptimalSolution in class SearchAlgorithm

Parameters:

source - The source of the new optimal solution.

solutions - The list of solutions.

solution - The new optimal solution.